Tag: eyes

Bacteria invisible to the naked eye find their way to many of the external surfaces of our bodies, including the naked eye. But the eye isn’t defenseless against this onslaught of microbes—researchers have found that it has special weapons for fighting back.

This fight happens at the surface of the cornea, the eye’s clear outer layer. New research published in the Journal of Clinical Investigation has found that keratin—a type of protein that gives structure to the cornea and other tissues like skin, teeth, hair, and mucous membranes—protects against bacteria. If the eye is like a fishbowl, it’s made of shards used for self-defense. Researchers say the new finding may lead to the creation of new kinds of antibiotics.

In the dreams of crime scene investigators, no doubt, they can feed a piece of hair into a machine and see a reconstruction of what the owner looks like. There’s a hint of that fantasy in the news that Dutch scientists have developed a test intended help police tell from a crime scene DNA sample the color of a suspect’s eyes. This information is gleaned from examining six single nucleotide polymorphisms, small genetic markers that are used in DNA fingerprinting, and could potentially help steer investigations when there are few other leads on a suspect and there is no match in police DNA databases. But the test, which can tell whether someone has blue, brown, or indeterminate (which encompasses green, hazel, grey, etc.) eyes with an average of 94% accuracy, doesn’t seem to have been tested outside of Europe, which raises questions about how well it would work in populations with greater diversity. It’s also a little hard to feature how you could bring this information to bear in a vacuum of other details—you’d want to avoid hauling someone in just because they looked suspicious and have the same eye color as the readout for the perp. At the moment, the test is not accurate enough to be introduced as evidence in court, which could be a bad thing or a good thing…depending on how many Philip K. Dick novels you’ve read.
Image courtesy of wetwebwork / flickr

What’s the News: Neuroscientists have found a preliminary answer to a question that has puzzled philosophers for centuries: If someone who has always been blind is one day able to see, can they recognize by sight objects they already know by touch? In a new study published online by Nature Neuroscience, patients who had been blind since birth underwent sight-restoring surgeries as children or adolescent. In the day or two following surgery, patients seemed unable to match what they felt with their hands with what they saw, the researchers found, but a week later, they could.

This results suggests that the brain doesn’t have the innate ability (or maybe has limited innate ability) to tie input from different senses to the same concept—but that it can learn, and pretty fast. Just how fast, the researchers wrote, suggests that the neuronal machinery needed to bring together visual and tactile information may already be there; it just has to be started up.

From across the pond comes a ravishing collection of scientific imagery. The Wellcome Collection, a London museum, has just announced the winners of its Wellcome Image Awards.

The 21 award winners, selected from images acquired by the Wellcome Collection over the last 18 months, were chosen both for their ability to enhance scientific understanding and for their aesthetic appeal. Many use colour to better illustrate hard-to-see features. [New Scientist]

When you’re nature’s ideal killing machine, perhaps color vision is merely an unnecessary affection. New research argues that sharks could be completely colorblind.

An Australian team led by Nathan Scott Hart investigated 17 shark species, peeking at the structure of their rod and cone photoreceptor cells in the retina. Human eyes come with red, green, and blue cone variations, allowing us to see in color. But not shark eyes. They appear to have just one kind of cone.

“Our study shows that contrast against the background, rather than color per se, may be more important for object detection by sharks,” Hart said. [CNN]

That, Hart says, may explain the common wisdom that sharks love yellow (and therefore you ought to avoid sunny swimsuits). It may be the reflective quality of yellow that catches a shark’s eye, not the hue itself.

“Bright yellow is supposed to be attractive to some sharks, presumably because it appears to the sharks as a very bright target against the water,” said Dr Hart. “So perhaps it is best to avoid those fluoro-yellow shorts next time you are in the surf.” [BBC News]

Spotting mistakes is a crucial part of typing (and indeed, life) and according to Gordon Logan and Matthew Crump, it’s a more complicated business than it might first appear. Using some clever digital trickery, the duo from Vanderbilt University found that the brain has two different ways of detecting typos. One is based on the characters that appear on the screen, and the other depends on the strokes of our fingers, as they tap away at the keys.

Logan and Crump asked 22 good typists to type 600 words presented on a screen, one at a time. Their efforts appeared below the target word, but all was not as it seemed. Throughout the experiment, Logan and Crump occasionally took control to the display. Sometimes, they put up the correct word, regardless of what the recruits actually typed so that their mistakes never appeared. On other trials, they deliberately introduced mistakes, which the typists hadn’t actually made.

To see whether the typists realized they were being toyed with, check out the full post at DISCOVER blog Not Exactly Rocket Science.

In studies (1, 2) in Nature Genetics that looked at more than 4,000 people, scientists report that variations in a gene called RASGRF1 are partly responsible for whether or not a person develops myopia.

“It is not quite the end of glasses yet but clearly the hope is that we will be able to block the genetic pathways that causes shortsightedness,” said Dr Christopher Hammond at King’s College London, an eye surgeon who led the British research. [The Telegraph]

A new study comparing Americans’ vision today to what it was like nearly 40 years ago says that our nation’s eyesight is getting worse as myopia, or nearsightedness, continues to become more prevalent. The study, led by Susan Vitale, appears in the Archives of Ophthalmology.

Vitale and colleagues used data from the National Health and Nutrition Examination Survey (NHANES) to compare the percentage of black and white Americans aged 12 to 54 with myopia in 1971-1972 and 1999-2004 [Reuters]. In the early 1970s only a quarter of people were nearsighted, but by the study’s 1999 to 2004 window that number had shot up to 42 percent.